The proposed project examines the physiological and psychological developmental origins of adaptive behavior and engagement in the classroom among children in Head Start. The primary thesis of this application is that individual differences in heart rate variability as assessed by vagal tone and in emotionality as assessed by measures of temperament have important implications for young children's readiness to learn. Specific objectives are to examine individual differences in vagal tone and emotionality and relate them to assessments of executive function and of behavior in the classroom. Prior work has noted relations between vagal tone and emotionality among middle SES samples but no study to date has examined relations between these variables among children facing socioeconomic disadvantage. Prior work has also noted relations between attention and anxiety in adult samples but no study has explicitly examined relations among negative emotionality, regulation, and executive function among children at risk for school failure. Neuroscientific study of the mind suggests relations among negative, particularly fearful, emotionality and the attention, planning, and problem solving abilities that comprise executive function. The developmental implications of these relations for child competence in school, however, have not been previously investigated. One hundred participants will be seen during the Head Start year and followed into kindergarten. During the spring of participants' Head Start year information will be collected on child emotionality, vagal tone, executive function, language, and classroom behavior. During the spring of participants' kindergarten year, information on child academic skills and classroom behavior will be collected. It is expected that the proposed research can provide valuable information with which to promote readiness among children at risk for school failure, and lay the foundation for ongoing programmatic investigation of school adjustment by the principal investigator and his graduate students. The proposed investigation extends the study of relations between emotionality and school adjustment downward to preschool and kindergarten age ranges, and goes beyond prior work to model developmental relations between cognition and emotion in the study of children's school adjustment and readiness to learn.